Our mission is articulated here and does not change: https://openai.com/charter/. As we say in the Charter, our primary means of accomplishing the mission is to build safe AGI ourselves. That means raising billions of dollars, without which the Nonprofit will fail at its mission. That's a huge amount of money and not something we could raise without changing structure.
Regardless of structure, it's worth humanity making this kind of investment because building safe AGI can return orders of magnitude more value than any company has to date. See one possible AGI application in this post: https://blog.gregbrockman.com/the-openai-mission#the-impact-...